[ODE] Problem interfacing ODE to my motor-control library
Remi.Coulom
Remi.Coulom at univ-lille3.fr
Mon Feb 21 14:05:06 MST 2005
Hello,
As I wrote in a previous post, I am trying to connect my motor-control
library to ODE. The problem I have is that I need a deeper access to the
simulation than what is provided by the stepping functions of the API.
According to what I have understood, I'll have to understand the
internals of ODE. Before I try to do that, I thought it might be a good
idea to ask the list for advice first, because I have no idea how
difficult it would be, or whether it is possible at all.
This is what I need: My library deals with systems where the dynamics
are linear with respect to control variables. That is to say, if the
state is described by vector x (positions, angles, velocities), and
control variables are vector u (forces, torques), then the dynamics are
given by:
dx/dt=A(x)*u + b(x)
A(x) is a matrix that does not depend on u. My control algorithms need
to be able to multiply a vector by the transpose of A(x).
In the simple 2D dynamics engine that I use, A(x) is obtained by
inversing a matrix. In fact, the matrix is not inversed. It is simply
LU-decomposed. I wonder if ODE has something similar, and how I could
have access to it.
Thanks for helping me,
Rémi
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